LOS ANGELES (CBSLA.com) — Michael Sam, now on the Dallas Cowboys practice squad, made headlines when he became the National Football League’s first openly gay player.

But nearly 40 years ago, Dave Kopay became one of the first pro athletes in a major sport to come out of the closet. Kopay, a running back, was in the closet throughout his playing days.

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He recently sat down with CBS2’s Rick Garcia about carrying around his NFL secret for years.

Garcia and Kopay walked around the rolling and lush Eagle Rock backyard garden Kopay designed and cultivates.

These days, he is a healthy, strong 72-year-old who once knocked helmets with the game’s best on Sundays.

Kopay piled up 1,469 all-purpose yards with five teams (San Francisco 49ers, Detroit Lions, Washington Redskins, New Orleans Saints and Green Bay Packers) from 1964 to 1972.

He had an all-American career at the University of Washington and played high school football at Notre Dame in Sherman Oaks. All that football cost a physical price so many of the game’s gladiators pay.

“I played with all the special teams,” Kopay says. “I did all the little things. I played one entire year in New Orleans with a separated shoulder, the entire year. They taped my shoulder.”

But it’s the emotional toll that almost killed Kopay.

He tells Garcia that at the lowest moment, he contemplated suicide.

“There were nights I was scared because I was so scared I didn’t know what I was going to do,” he says. “I was lonely … miserable.”

To this day, it’s painful for  Kopay to talk about the secret he kept from his band of brothers and his family: He hid the fact that he is gay.

And the hiding, he says, choking up: “It’s horrible.”

Being taunted by guys in the locker room is one thing, but facing the abuse so many gays face in their own homes is entirely another.

Kopay told Garcia his Roman Catholic mother and drill instructor father were both devastated when he told them the news.

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“Family love, it’s a difficult thing sometimes,” Kopay says. “I used to wonder. Do they really love me or not? When I told my mom that I was gay, she totally lost it. It was horrible. My dad also had a negative reaction. I think only because he was trying to support my mom.”

He tried to deny his feelings. He tried the partying social scene that many pro-athletes enjoy. And his all-American good looks left no shortage of interest from women. Kopay even married one.

He went into therapy, and his therapist tried to convince him that he was straight.

“I told him he was full of crap, and I argued with him,” Kopay remembers. “I loved her, but I should never have married her.”

The marriage didn’t survive, and he knew he had to keep his secret and his feelings to himself.

When Washington Redskins teammate Jerry Smith anonymously came out to a reporter for a newspaper article, Kopay decided it was time.

After his announcement in 1975, Kopay wrote a book, then hit the talk-show circuit, figuring he could make a difference.

“I was really, really wiped out after a year of doing that,” he recalls. “But I also was totally invigorated. I knew it was what I needed to do to contribute to society. To feel like I was making a difference.”

He quickly found out that nothing was changing. It took nearly 40 years for the next monumental moment.

Last year, NBA player Jason Collins announced he is gay. And then in February, former University of Missouri football star Michael Sam came out. A few months later, he was drafted by the St. Louis Rams, which led to this controversial celebration, including a kiss, on live TV between Sam and his boyfriend.

“Because I’m from the old school,” Kopay says, “I’m not sure I would have handled it that way. I might have given him a big hug. But I’m not sure I would have given him the pie in the face, the whole business, you know.”

While Dave finds some comfort and even a little redemption in recent revelations by public figures coming out, he still thinks there’s a long way to go.

“I was so proud of Jason Collins, the way he came out and handled himself,” Kopay says. “And look what Billie Jean King has accomplished. I take a little satisfaction in that. She told me that my book so helped her. That’s an incredible feeling, Dave, you’ve done something good, you know.”

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Back in February, Kopay wrote an open letter to Michael Sam. In the letter, Kopay told Sam to “go out, stand tall and be proud of all you are.”